1.^ 



iicurileiniua i.s hrokeu ut intervals by small biuullcs of 

 axis cylinders from the ganglion cells, which can be traced 

 into the filjrons core. Scattered nuclei are found inside 

 the fibrous core, for the most part just inside the inner 

 neurilemma, though a few may be seen about the centre of 

 it. These are the nuclei of the neuroglial cells, whose 

 branched processes form the supporting groundwork of 

 the nervous system. The hbrous core itself is composed 

 of: — 



(1) Fibres of the neuroglial cells, which stain with 

 many reagents (r.c/., eosin), and compose the bulk of the 

 core. 



(2) Xerve tubules, consisting of homogeneous axis 

 cylinders which are usually unstained by leagents, and 

 [)robablv in life consist of a semi-fluid substance bounded 

 by a fine spongio-plasmic sheath. These tubules are very 

 small, and are for the most part scattered about inside the 

 fibrous core, though neai- the centre a large space is seen, 

 more or less circular in outline in transverse section, 

 which is found throughout the whole length of the core, 

 and probably represents a bundle of nerve tubules. 



{'■]) Irregular spaces containing fluid.* 



Eeturning now to the general arrangement of the 

 neryous system, it has already been mentioned that the 

 lateral nerve cords dilate anteriorly to form the biain. 

 This structure is composed of a dorsal and a ventral ceie- 

 bral ganglion on eithei- side. The ventral ganglion is 

 merely the expanded end of the lateral cords, and it is 



-It should be mentioned that the above view of the iiatui-e of the 

 elements of the nervous coic is that advoeated by Montgoniery (loc. eit. 

 p. 428). Biirger on the other hand (Die Nemcrtinen, Fauna und Floi-a dew 

 Golfcs von Neapel Bd. XIX., 1895) supposes the densely staining elements, 

 considered to be neuroglial processes on the above view, are the nervous 

 fibrils, and that the so-called nerve tubules are clefts filled witli Ihiid. 



